| 摘要 |
PURPOSE:To enable the inspection of the output port at a microconputer by discriminating the signal level of a check port. CONSTITUTION:As an inspection signal (a) is transmitted to a microcomputer 2 due to start of the engine or others, an output port P10 is set at the prescribed signal level while the signal output is fed to a check port P20 connected to a signal line. Then, after a specified time, the signal level of the port P20 is determined whether it is at the set level or not and when it is at the prescribed level, the inspection is finished and a shift is made to a specified control. When the signal level of the port P20 differs from the prescribed level, an signal indicating the abnormality of the port P10 is generated. Therefore, the discrimination of the operation of the output port P10 can be done by checking the signal level of the check port P20. This prevents such troubles as failure in normal signal outputting and abnormality in the control with fixing at the specified signal output due to hard errors of the output port P10.
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